(CNSNews.com) – Voters in Nigeria appear to have handed a four-year term to President Goodluck Jonathan, in an election result underlining the deep north-south, Muslim-Christian divide in Africa’s most populous country.

As of early Monday, results released by the Independent National Electoral Commission (INEC) showed People’s Democratic Party (PDP) candidate Jonathan, a Christian southerner, leading Muhammadu Buhari, a Muslim from the north, by a 59-32 point margin.

The breakdown of states’ results from Saturday’s election clearly illustrates the geographic and religious splits: Buhari, and former military ruler and candidate for the Congress for Progressive Change (CPC), won all 12 of Nigeria’s states where shari’a law has been introduced since 1999.

Buhari’s showings in those states, all in the north, ranged from around 52 percent in Kaduna state to almost 80 percent in Borno.

In the far south Niger Delta, by contrast, Jonathan swept the region, achieving well over 90 percent in at least nine states, INEC results showed.

The months leading up to the election were marred by violence that killed almost 100 people, and there were several bombings on the eve of the election and on election day, in Borno and Kaduna states.

Nonetheless, observers from the Economic Community of West African States (ECOWAS) regional group assessed that the poll was “free and transparent” – a significant achievement in a country where the last two elections held since the end of military rule, in 2003 and 2007, were both characterized by widespread intimidation and ballot-rigging.

Early signs after the current election were not promising, however.

After the polls closed, rioting and destruction of property was reported in Bauchi and Gombe, two of the shari’a states in the north, where youths identified as CPC supporters attacked properties and vehicles of PDP members. Nigerian media reported that at least 10 people were killed in the violence.

Nigeria is the world’s seventh-largest oil exporter, and instability in the country, which has also long grappled with corruption, can have implications far beyond its borders.

Its population of 155 million is around 50 percent Muslim and 40 percent Christian, and tensions between the two groups have periodically erupted into violence, especially in the north and in the central Plateau state, which is located roughly on the Muslim-Christian divide. (According to INEC Jonathan took around 73 percent of the vote in Plateau in Saturday’s vote.)

A U.N. body that monitors racial discrimination estimates that more than 13,500 people have died in ethnic and religious violence in Nigeria over the past 10 years.

Even Jonathan’s candidacy in the election gave rise to some tension arising from his religious affiliation.

The PDP, which has been in power since the end of military rule in 1999, has had an unwritten agreement that the Christian south and Islamic north rotate the presidency, an arrangement designed to reduce the chances of ethnic and religious strife.

Jonathan, a former deputy president, was elevated to the presidency after President Umaru Yar’Adua died in May 2010

Women line up to cast their votes in Mashi, Nigeria on Saturday, April 16, 2011 (AP Photo/Sunday Alamba)

Yar’Adua, a Muslim northerner, succeeded a two-term Christian from the south in 2007. Since Yar’Adua’s term ended early with his death, many Muslims felt it appropriate that the next elected president should be a Muslim.

John Campbell, a former U.S. ambassador to Nigeria, warned in a Foreign Affairs magazine article last year that an end to the north-south rotation “could lead to postelection sectarian violence, paralysis of the executive branch, and even a coup.”

In an audio message released in 2003 Osama bin Laden named Nigeria as one of six “most qualified regions for liberation” by Islamic warriors (the others were Saudi Arabia, Yemen, Pakistan, Morocco and Jordan.) He called on Muslims in the six countries to take steps “to establish the rule of Allah on earth.”

A Pew Global Attitudes Project surveying the views of Muslims in seven key countries late last year found that 49 percent of Nigerian respondents expressed a favorable opinion of al-Qaeda – 15 percent more than the country with next highest score, Jordan.

In response to another question in the survey, 34 percent of Nigerian respondents said suicide bombings could be justified in defense of Islam, a small cohort than in Lebanon (39 percent), but larger than those in the other countries surveyed – Egypt (20), Jordan (20), Indonesia (15), Pakistan (eight) and Turkey (two percent.)